The present invention relates generally to an agitator apparatus, and more particularly to a horizontal agitator suitable for use in the food, dairy and beverage industries.
In light of recent food safety issues, the USDA has become more aggressive in its acceptance criteria and inspections of equipment used in the food, dairy and beverage industries. The USDA has promulgated standards related to the cleanliness and cleanability of equipment used in these industries. Due to these standards, it is becoming increasingly more important for food, dairy and beverage producers to have equipment that is USDA accepted to stay competitive in the marketplace.
Agitators, and more particularly horizontal agitators, for use in the food, dairy and beverage industries are known in the art. Conventional agitators generally include an impeller attached to a rotatable shaft that is supported by a body. The body is placed within the wall of a storage tank so that the impeller blades are positioned toward the interior of the tank. The end of the shaft that is outside the storage tank is generally attached to a motor or other means to cause rotation of the shaft.
Conventional agitator designs suffer from several limitations that render them difficult to achieve USDA acceptance. In one known agitator design, an owner is required to climb into the tank, manually remove the exposed parts and individually clean the parts by hand. In another known agitator design, cleaning fluid is forced through the body and exits the nose of the agitator at high pressure to clean the impeller blades. In this design an owner is required to loosen a shaft collar and push the shaft forward by hand to disengage a nose seal from the agitator body. The movement of the shaft enables cleaning fluid to flow through the interior of the body to effectively clean the body and adjacent sealing surfaces. After cleaning, the owner must manually pull the shaft back and retighten the collar before operation. Over-tightening the collar can result in damage to the nose seal and under-tightening allows leakage into the body during a mixing operation.
Those skilled in the art continue to attempt to improve upon the designs of current horizontal agitators, particularly to improve their cleanability for USDA acceptance. The present invention provides an effective USDA-accepted, mechanically cleaned-in-place (CIP) horizontal agitator.
The present invention recognizes the aforementioned limitations associated with conventional horizontal agitators and provides a USDA-accepted, mechanically cleaned-in-place horizontal agitator assembly.
In accordance with an embodiment of the present invention, a horizontal agitator assembly is provided that includes an impeller secured to a shaft that is rotatably supported within a body. A sealing member is positioned on the shaft between the impeller and a distal end of the body to prevent the ingress of matter into the body. The body of the agitator assembly is disposed within the wall of a storage tank and is secured to the storage tank by a mounting assembly. The body is preferably a one-piece design having internally smooth surfaces that are free from crevices that can facilitate collection of undesirable foreign matter, such as bacteria. The body includes a rear seal assembly having a connection member attached thereto to secure the agitator assembly to a cleaning fluid source. A bushing comprising a self-lubricating polymer is disposed near the distal end of the body to support the shaft. The bushing is provided with internal and external grooves that allow passage of the cleaning fluid to effectively clean the shaft and impeller.
The mounting assembly supports the weight of a motor assembly that supplies rotative power to the shaft. A shaft housing is rotatably supported within the motor assembly and provides a means to attach the shaft to the motor assembly. An area of the shaft that is positioned within the shaft housing contains a plurality of radially extending teeth that engage the shaft housing. The end of the shaft opposite the impeller includes a plurality of threads that engage the internal threads of a shaft collar that is positioned on the shaft. A compressible member is positioned on the shaft between the shaft housing and the shaft collar.
During a CIP cycle, cleaning fluid enters the port in the rear seal assembly and travels between the body and the shaft to effectively clean the internal surfaces of the agitator assembly. A portion of the cleaning fluid is forced through the internal grooves of the bushing to clean the area of the shaft in proximity with the bushing. The remainder of the cleaning fluid is forced through the external grooves until it reaches the sealing member. Upon reaching the sealing member, the fluid pressure increases until the pressure overcomes the biasing force of the compressible member and forces the sealing member and shaft to move axially away from the distal end of the body permitting the cleaning fluid to escape. The escaping fluid is redirected by the contoured geometry of the distal end of the body to provide pressurized mechanical cleaning of the impeller blades and adjacent sealing surfaces during the CIP cycle.